Abstract
A theoretical calculation of the electronic structure of a hypothetic \(\text{AcO}_{8}^{12-}\) cluster with symmetry point group D4h is performed in the self-consistent field approximation of the relativistic discrete variation method. It describes a fragment of the crystal lattice of actinide dioxides. The molecular orbital scheme and the histogram of the valence electron X-ray photoelectron spectrum (XPS) are plotted in the binding energy range from 0 eV to ~40 eV. These calculations are required for understanding features of the chemical bond nature and the structure of the valence electron XPS spectrum in actinium oxide. As in the entire series of actinide dioxides, significant covalence effects are noted in \(\text{AcO}_{8}^{12-}\) which are caused by a considerable overlap of not only Ac 6d, 6p atomic orbitals (AOs) but also unoccupied Ac 5f AOs with oxygen AOs.
